Apparatus for testing fabrics and other sheet materials

ABSTRACT

Apparatus for testing fabrics and the like for wearability and generally comprises a generally horizontally extending base member including a broad upper surface, an anvil member having a longitudinally extending lofty upper-side, clamp means at the two anvil ends for removably attaching the test fabric in stretched condition above the anvil upper-side, a shoe member overlying the anvil and adapted to firmly downwardly abut the test fabric, powering means ultimately attached to the shoe member for causing repeated longitudinally reciprocatable movement thereof over a lengthy time period while abutting the test fabric, and other desirable features for implementing the apparatus purposes. For preferred apparatus embodiments, a pair of transversely separated anvil members are employed whereby the same kind of woven fabric can be tested simultaneously for wearability both in the warp and weft directions of the test fabrics.

United States Patent [1 1 Schneider et al.

[ Sept. 17, 1974 APPARATUS FOR TESTING FABRICS AND OTHER SHEET MATERIALS [75] Inventors: Charles Schneider; George A.

Goodman, both of Omaha, Nebr.

[73] Assignee: Charles, Inc., Council Bluffs, lowa [22] Filed: June 4, 1973 [21] Appl. No.: 366,708

[52] US. Cl. 73/7, 73/159 [51] Int. Cl. G01n 3/56 [58] Field of Search 73/7, 159

[56} References Cited UNITED STATES PATENTS 1,841,167 1/1932 Weinberg 73/7 3,286,505 11/1966 Penman 73/7 Primary ExaminerDonald O. Woodie] Attorney, Agent, or Firm-George R. Nimmer [5 7 ABSTRACT Apparatus for testing fabrics and the like for wearability and generally comprises a generally horizontally extending base member including a broad upper surface, an anvil member having a longitudinally extending lofty upper-side, clamp means at the two anvil ends for removably attaching the test fabric in stretched condition above the anvil upper-side. a shoe member overlying the anvil and adapted to firmly downwardly abut the test fabric, powering means ultimately attached to the shoe member for causing repeated longitudinally reciprocatable movement thereof over a lengthy time period while abutting the test fabric, and other desirable features for implementing the apparatus purposes. For preferred apparatus embodiments, a pair of transversely separated anvil members are employed whereby the same kind of woven fabric can be tested simultaneously for wearability both in the warp and weft directions of the test fabrics.

9 Claims, 3 Drawing Figures APPARATUS FOR TESTING FABRICS AND OTHER SHEET MATERIALS Those engaged in the converting and processing of sheet materials, such as textiles, fabrics, leathers, papers, etc., have developed various apparatus for testing the sheet materials for wearability under actual use conditions. For example, as described in US. Pat. No. 2,189,589 (Mahannah, 1940), paper mills commonly subject their fibrous cellulosic sheet material to abrasion tests in an effort to predict the resistance of stationery papers to pencils and erasers. Similarly, as described in US. Pat. Nos. 1,632,591 (Dennis, 1927) and 2,590,839 (Clapharn, 1952), textile mills commonly subject their woven sheet material fabrics to abrasive tests in an effort to predict their wearability for clothing, awnings, upholstery, etc. However, apparatus of the prior art for testing wearability of sheet materials has tended to be quite expensive and thus largely limited for use by the sheet material manufacturers or by commercial testing laboratories. Accordingly, many sheet material converters, which are likely to be relatively modest economic units such as a small upholstery shop or even a typical furniture manufacturer, are forced to rely upon reports received from a geographically remote sheet material testing site. Not only is such reliance costly and time consuming for sheet material converters, the test data is likely to be improperly correlated for the use purposes intended by a specific converter. Ideally, wearability testing should be performed in house by the furniture maker or other converter of sheet materials because the converter is in the best position to judge the applicability of the sheet material for the intended use. Not only would such in house wearability testing save time and money for the converter, it would also allow him to readily adapt to unusual or unexpected use situations for the sheet material. Moreover, for those converters who purchase sheet material supplies from various manufacturing mills, an unbiased objective comparison of competitively manufacturers wares would become readily available.

In the furniture trade, wearability of the furniture covering upholstery fabric depends upon several variables, and for this industry in house testing is particularly desireable. Upholstery fabric wearability depends upon the overall contour and use conditions of the selected furniture article. For example, in the case of woven textile fabrics it has been long recognized that wearability in the fabric warp and weft (i.e. the fill) directions can be vastly disparate. Accordingly, it would be beneficial for the upholsterer to have readily available both the warp and weft wearability for each specific textile material so as to allow him to then apply the covering in the appropriate directions along the specifically encountered furniture article. Moreover, with many of the fabric wearability testers of the prior art, the testing apparatus abrasion action is apt to be grossly inappropriate and non-correlative for actual use conditions. In this vein are included rotating abrasive wheels and discs which do not even remotely similate the frictional forces between furniture covering and the clothing of the furniture occupant.

It is accordingly the general object of the present invention to provide improved apparatus for testing the wearability of sheet materials such as leathers, papers, textile fabrics and the like. It is an ancillary general object to provide improved apparatus for testing the resistance of sheet materials, and particularly upholstery fabrics, to withstand frictional or abrasive forces.

It is another general object of the present invention to provide apparatus for testing the wearability of textiles and other sheet materials, which apparatus is not only reliable but also relatively inexpensive for availability to in house testing by relatively economically modest sheet material converters. It is a further ancillary general object to provide reliable and economical testing apparatus, which is versatile in that a specific converter can modify the apparatus for his own peculiar intended purposes.

It is another object to provide apparatus of the abrasion type for testing the wearability of furniture upholstery fabrics, and wherein the overall apparatus and including the reciprocating abrasion element yield test data unusually well correlated to actual use conditions of furniture articles.

It is a further object to provide apparatus for testing the wearability of upholstery fabrics in the warp and weft directions simultaneously whereby the furniture upholsterer is apprised not only of the fabrics general character, but also the appropriate directions for employing same along the encountered furniture contour.

It is yet another object to provide apparatus for testing the wearability of fabrics and other sheet materials exceedingly quickly and reliably by a person of average skill and having only moderate training.

With the above and other objects and advantages in view, which will become more apparent as this description proceeds, the apparatus for testing textile fabrics and other sheet materials generally comprises a generally horizontal base member, an anvil member having a longitudinally extending upper-side located loftily above the base member, novel resiliently yieldable clamp means for mounting the sheet material to be tested in overlying working-surface relationship to the anvil upper-side, a shoe member over-lying the anvil upper-side and adapted to frictionally abut the sheet material to be tested, powering means for causing the shoe member to reciprocate vigourously longitudinally while abrading the sheet material and for a selected testing duration, and (for simultaneous warp and weft testing) a pair of anvil and shoe members together with novel means for reciprocatably supporting and powering the shoe members.

In the drawing, wherein like characters refer to like parts in the several views, and in which:

FIG. 1 is a top plan view of a representative embodiment A" of the apparatus of the present invention.

FIG. 2 is a sectional elevational view taken along lines 22 of FIGS. 1 and 3, which is a substantial mirror image of a sectional elevational view taken along lines 2A-2A of FTGS. 1 and 3.

FIG. 3 is a sectional elevational view taken along lines 3-3 of FIGS. 1 and 2.

Apparatus embodiment A is intended for the si-.

multaneous testing of two elongate sheet material strips, such as two strips of the same textile fabric extending longitudinally in the warp (101) and the weft (102) directions. However, if embodiment A were to be divided into substantially identical halves by an imaginary longitudinally extending medial verticalplane 9, each apparatus half might be employed for the testing of a single sheet material strip. Accordingly,

structural description will be devoted primarily to the apparatus half seen in the sectional elevational view taken along lines 2-2, the sectional elevational view taken along lines 2A-2A being a substantial mirror image thereof.

Representative embodiment A generally comprises a generally horizontally extending base member 10, herein of constant vertical thickness between a pair of broad planar horizontal surfaces including upper surface 11 and lower surface 12. The base member is herein selected of rectangular shape including a transversely extending fore-end 13, a transversely extending back-end 14, a longitudinally extending right-end 15, and a longitudinally extending left-end 16. The longitudinally extending imaginary vertical-plane 9 is, for the purposes of reference, herein defined to intersect base member 10 midway between and parallel to right-end and left-end 16. i

There is an anvil member including a substantially horizontal broad planar upper-side 21 located loftily.

above the base member upper surface (11). Anvil member upper-side 21 is herein selected of longitudinally elongate rectangular shape including a transversely extending front-edge 23, a transversely extending rear-edge 24, a longitudinally extending right-edge 25, and a longitudinally extending left-edge 26. As best seen in FIG. 2, anvil embodiment 20 might be singularly constructed throughout of a structural material such as metal and including a horizontal table 21T to define anvil upper-side 21, an upright front-wall 23T defining front-edge 23, and an upright rear-wall 24T defining the rear-edge 24. The anvil member is attached to the base member, herein immovably attached through vertical bolts 27 passing through the horizontally flanged lower ends of the respective walls 23T- 24T and base member 10. If the sheet material to be tested is a textile fabric, the immediately underlying horizontal support therefor is desireably of a resiliently compressive structural material. Accordingly, if the anvil table (21T) be of mettalic hardness, a separate layer (22) of polyurethane of similarly resiliently compressive resinous material is desireably laminated or otherwise attached conterminiously along the anvil edges (e.g. rectangular layer 22 conterminous along edges 23-26). In such situations, the upper surface of topical layer 22, rather than the anvil upper-side 21, would be defined as the anvil work-surface for directly underlying the sheet material to be tested.

The sheet material to be tested for wearability is through the mechanism of a repeatedly longitudinally reciprocating shoe member (e.g. 50). Thus, the sheet material strip to be tested needs to be removably securely applied in overlying abutting relationship with the anvil work-surface, e.g. 22. In this vein, a pair of clamps are employed terminally of the anvil front and rear portions, herein taking the form of a front-clamp 30 and a rear-clamp 40 longitudinally separated by anvil 20 and spatially separated from front-wall 23T and rear-wall 24T, respectively. Rear-clamp 40 takes the form of a rigid L-shaped bracket having an uprightwall 41 and a bottom-flange 42 which is herein immovably attached to base member 10 with bolts 43. Extending horizontally rearwardly of upright'wall 41 is a threaded stud 44, and a clamp-plate 45 loosely surrounds stud 44. A wing nut 46 threadedly engaged with stud 44 is adapted to longitudinally motivate clampplate 45 toward upright-wall 41 and thereby secure one transverely extending end of the sheet material sample to be tested, e.g. 101, 102.

For many situations, especially involving textile fabrics, the sheet material to be tested needs to be in tightly longitudinally stretched condition during reciprocational abrasive testing thereof. For such purpose, there are clamp-tensioning means tending to maximize the longitudinal distance between the frontclamp and the rear-clamp during the actual period of abrasion testing. However, the longitudinal distance between the front-clamp and the rear-clamp needs to be of temporarily reduced length to facilitate clamping and declamping of the test sheets. For example, as indicated in phantom line in FIG. 1, rear-clamp 40 might be stationary and front-clamp 30 might be longitudinally movable. In such situations, front-clamp 30 might comprise an upright-slab 31 having its lower end resting upon base upper surface 11 and longitudinally reciprocatably slidable therealong. Extending horizontally rearwardly of upright-slab 31 is a threaded stud 34, and a clamp-plate 35 loosely surrounds stud 34. A wing nut 36 threadedly engaged with stud 34 is adapted to longitudinally motivate clamp-plate 35 toward upright-slab 31 and thereby secure the other end of the sheet material sample to be tested.

Preferably, the temporary length reduction between the front-clamp and the rear-clamp is attained through a longitudinally resiliently yieldable clamp-tensioning means. For example, there is a substantially horizontal longitudinally extending spacer-rod 37 located in elevation between base member 10 and anvil table 21T, said spacer-rod 37 passing through an enlarged opening 29 of anvil front-wall 23T and having its rearward end passing through reawvall 24T and removably secured thereat with nut 37R. The forward end of spacer-rod 37 passes through and is removably threadedly secured at nut 37F at upright-slab 31 of front-clamp 30. There is a longitudinally elongate helical spring 38 surrounding spacer-rod 37 and bearing against a longitudinally movable clamp, herein said helical spring being longitudinally confined between anvil rear-wall 24T and upright-slab 31. Thus, the helical spring 38 normally urges movable front-clamp 30 in the forward direction as indicated in solid line in FIG. 1. Moreover, the helical spring 38 is readily removable from the apparatus, as by the threaded members 37R and 37F. Accordingly, the fabric longitudinal tension is selectable depending upon the tension resiliency characteristics for the chosen helical spring (38). Moreover, minor adjustments of the fabric tension can be afforded through intervening spacers or washers (not shown) along spacerrod 37.

As had been previously alluded to, and as indicated in double-headed arrows in FIGS. 1 and 2, a repeatedly longitudinally reciprocatable shoe member (e.g. 50) is employed to abrasively test the sheet material for wearability. It will be seen that the longitudinally reciprocating non-roller form shoe member is uniquely adaptable for testing the wearability of fabrics and especially for furniture upholstery fabrics. As seen in FIG. 2, shoe member 50 is of generally arcute shape including a linearly generated convex lower surface 51 which makes actual abrasive contact with the tested sheet material. Shoe 50 is rigidly non-rotatably connected to the lower portion os an upright support-bar 52, and in top plan view shoe 50 has a pair of parallel longitudinally extending sides. With such configuration, various removably attachable laminae might be selected for the shoe lower extremity 51, such as textile fabrics, leathers,

sheet metals, etc. In this vein, it has been found that the use of removably attachable metallic mesh is desireable for the shoe lower extremity 51 and closely correlates wearability over relatively short test durations. It is desireable to temporarily elevate the shoe member while clamping and de-clamping test sheets, and in this regard, upright support-bar upper portion is slidably surrounded by a tubular collar 53 maintained at constant lofty elevation above the anvil working-surface. A setscrew 54 passing through collar 53 and bearing against support-bar 52 maintains the temporary increase in shoe member elevation. Shoe-tensioning means for applying a known downward force of the reciprocatable shoe member against the test sheets is desireable. In this regard a coil spring 55 surrounding support-bar 52 below tubular collar 53 might be employed. Preferably, the support-bar 52 upper portion is of uniform crosssectional shape to permit its disengagement from collar 53. In this way, the coil spring 55 is removably substitutable whereby the shoe member downward force against the tested sheet is selectable depending upon the tension resiliency characteristics of the coil spring (55) chosen.

In order to repeatedly longitudinally reciprocate the shoe member abrasively along the tested sheet, the shoe member is ultimately connected to a substantially horizontal longitudinally extending track means. Herein, the track means takes the form of a substantially horizontal rail 60 parallel to vertical-plane 9 and longitudinally lengthier than the anvil working-surface, e.g. 22. Track rail 60 is maintained in elevation above and parallel to base upper surface 11 with a pair of angular brackets including rear-bracket 64 herein located transversely offset of vertical-plane 9 and a single transversely wider front-bracket 63 intersecting said vertical-plane 9. The brackets 63 and 64 are immovably attached to base member as by bolts 62, and the rails 60 are maintained in longitudinally arrested relationship as through threadedly engaged nuts 61. Longitudinal reciprocatability for the respective shoe abraders 50 is herein provided through ultimate connection with a cylindrically tubular slider member 65 surrounding and longitudinally slidably movable along the track rail 60. With the dual anvils embodiment A, there are along the two respective rails 60 two slider members 65 which are rigidly tied together in co-reciprocatable relationship with a transversely extending web 66 intersecting vertical-plane 9. Appropriate to such dual anvils embodiment is a sturdy columnar member 67 extending rigidly vertically upwardly from web 66 and lying within vertical-plane 9. Rigidly and nonrotatably connected to the upper end of column 67 is a transversely extending beam 68, the leftward and rightward ends of said beam 60 being rigidly and non-rotatably connected to the respective tubular collars 53.

There are powering means attached to the one or more shoe member abraders tend for causing repetitive longitudinally reciprocatable movement thereof and for an extended time duration. Herein, said powering means comprises an electric motor 70 immovably attached to base member 10, such as nearer the back-end 14 thereof and wholly transversely offset of verticalplane 9. Corevolvably attached to the motor revolving shaft 71 is some selectable eccentric means, herein as a circular disc 72 that is transversely offset from vertical-plane 9. Connection between the eccentric means and the shoe member is a longitudinally extending elongate crank-arm. Crank-arm 75 herein lies along vertical-plane 9 and has its forward portion pivotably connected with pin 76 to the rearwardly extending ears 69 of web 68. The rearward portion of crank-arm 75 is pivotably connected with pin 77 to disc 72 at some radial distance from motor shaft 71 thereby providing a revolving eccentric means that causes longitudinally reciprocatable movement of shoe abraders 50 through intervening reciprocatable slider 65. It is desireable that the pivot pin 77 be positionable a selectable distance from revolving shaft 71, as by providing a plurality of incrementally radially spaced holes (hidden lines) in disc 72, thereby providing a selectable stroke length for the crank-arm. Rheostats or the like might be employed to govern the angular velocity of motor shaft 71 to provide further operational flexibility for the testing apparatus. The operational direction of the powering means and hence the number of reciprocations for the shoe members abraders along the tested sheet might be governed by suitable counting mechanism, such as the well-known Veeder Root type.

It can thus be seen that the apparatus concept of the present invention for testing the wearability of textile fabrics and other sheet materials has several unique structural features which provide reliable test results. Moreover, these unique structural features provide a highly versatile testing apparatus that can be readily modified in several respects according to the specifically encountered sheet materials to be tested. Among the permitted apparatus modifications are: degree of stretch applied to test material, the texture and also the degree of downward pressure for the shoe abrader, the shoe abrader stroke length and its frequency of reciprocation, and frictional engagement characteristics between the test sheet and the underlying anvil.

From the foregoing, the construction and operation sheet materials testing apparatus will be readily understood and further explanation is believed to be unnecessary. However, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the appended claims.

What is claimed is as follows:

1. Apparatus for testing the expected wearability of fabrics and other sheet materials, said apparatus comprising:

A. A generally horizontally extending base member including a broad upper surface therefor;

B. An anvil member attached to the base member and including a generally horizontal longitudinally extending broad upper-side located loftily above the base member upper surface, said anvil member upper-side extending lengthily longitudinally be tween two transversely extending anvil edges including a front-edge and a rear-edge;

C. A pair of clamps including a front-clamp and a rear-clamp located terminally of and separated by said anvil, said clamps being adapted to removably attach a longitudinally extending sheet material test strip in stretched condition in overlying relationship with a working-surface anvil portion near the upper-side thereof;

D. Clamp-tensioning means tending to maximize the longitudinal distance between the front-clamp and the rear-clamp, said clamp-tensioning means being longitudinally resiliently yieldable for temporarily reducing the distance between said clamps;

E. A generally horizontal longitudinally extending track means attached to the base member and located above the base member upper surface;

F. A shoe member of vertically adjustable elevation and overlying the anvil upper-side, said shoe member being longitudinally reciprocatably associated along said track means;

G. Shoe-tensioning means tending to press the shoe member downwardly toward the anvil and the test sheet stretched therealong; and

H. Powering means attached to the shoe member for causing longitudinally reciprocations of the shoe member.

2. The apparatus of claim 1 wherein the anvil upperside has a resiliently compressible pad superimposed upon and attached to said anvil upper-side whereby the longitudinally stretched and removably clamped test sheet material is in firm abutment downwardly against said pad as an anvil supported working-surface.

3. The apparatus of claim 1 wherein the track means comprises at least one substantially horizontal longitudinally extending rail maintained at substantially constant elevation loftily above the base member upper surface, there being a slider member slidably surrounding and longitudinally reciprocatably movable along said track rail, and the shoe member being ultimately connected to the slider member and co-reciprocatable therewith.

4. The apparatus of claim 3 wherein the powering means comprises an electric motor including a revolvable eccentric-means thereon, and an elongate crank arm pivotably connected to said revolvable eccentricmeans and also to said longitudinally reciprocatably movable slider member.

5. The apparatus of claim 1 wherein the clamptensioning means comprises a substantially horizontal longitudinally extending elongate helical spring bearing against a clamp member and removably attached to the apparatus whereby the sheet material stretching tension is selectable depending upon the tension characteristics of the chosen helical spring.

6. The apparatus of claim 5 wherein said elongate helical spring surrounds a substantially horizontal longitudinally extending spacer-rod having at least one terminus thereof removably attached to a clamp member to facilitate helical spring substitution for selectable tension upon the sheet material.

7. The apparatus of claim 1 wherein the shoe member is attached to the lower portion of an upright support-bar, the support-bar upper portion being slidably surrounded by a tubular collar maintained at constant elevation above the base member upper surface, a set-,

screw passing through the tubular collar to vertically adjust the shoe member elevation whenever the apparatus operator is clamping andeclamping the tested sheet material, the shoe-tensioning means comprising a coil spring surrounding the support-bar between the shoe member and the upright tubular collar, said coil spring being removable from surrounding relationship with the support-bar whereby the shoe member downward force against the tested fabric is selectable depending upon the tension resiliency characteristics of the chosen coil spring.

8. The apparatus of claim 7 wherein the shoe member comprises a removably connected bottom-panel portion of selectable texture and for making firm though reciprocatable contact with the tested sheet material.

9. The apparatus of claim 1 adapted for simultaneously testing the same kind of textile fabric sheet material in the warp and weft directions thereof, there being a pair of anvil members in substantial parallelism and spaced on opposite sides of an imaginary longitudinally extending vertical-plane; wherein each of said anvil members is provided with a pair of terminal clamps and further comprises independent clamptensioning means for each pair; wherein the track means comprises a pair of substantially horizontal longitudinally extending elongate parallel rails located between the anvils and maintained at substantial coelevation above the base member upper surface, each of said track rails being provided with a slider member slidably surrounding and longitudinally reciprocatably movable therealong, said slider members being attached together in co-reciprocatable relationship with a transversely extending web; wherein there is a pair of shoe members overlying the respective anvil members, each of said shoe members being ultimately connected to a sturdy columnar member extending rigidly uprightly from said transversely extending web; and wherein the powering means comprises an electric motor connected to the base member and including revolving eccentric means, and an elongate crank-arm lying along said imaginary upright-plane and being pivotably connected both to the motor shaft through the eccentric means carried thereby and also to the slider members connecting transverse web. 

1. Apparatus for testing the expected wearability of fabrics and other sheet materials, said apparatus comprising: A. A generally horizontally extending base member including a broad upper surface therefor; B. An anvil member attached to the base member and including a generally horizontal longitudinally extending broad upper-side located loftily above the base member upper surface, said anvil member upper-side extending lengthily longitudinally between two transversely extending anvil edges including a front-edge and a rear-edge; C. A pair of clamps including a front-clamp and a rear-clamp located terminally of and separated by said anvil, said clamps being adapted to removably attach a longitudinally extending sheet material test strip in stretched condition in overlying relationship with a working-surface anvil portion near the upper-side thereof; D. Clamp-tensioning means tending to maximize the longitudinal distance between the front-clamp and the rear-clamp, said clamp-tensioning means being longitudinally resiliently yieldable for temporarily reducing the distance between said clamps; E. A generally horizontal longitudinally extending track means attached to the base member and located above the base member upper surface; F. A shoe member of vertically adjustable elevation and overlying the anvil upper-side, said shoe member being longitudinally reciprocatably associated along said track means; G. Shoe-tensioning means tending to press the shoe member downwardly toward the anvil and the test sheet stretched therealong; and H. Powering means attached to the shoe member for causing longitudinally reciprocations of the shoe member.
 2. The apparatus of claim 1 wherein the anvil upper-side has a resiliently compressible pad superimposed upon and attached to said anvil upper-side whereby the longitudinally stretched and removably clamped test sheet material is in firm abutment downwardly against said pad as an anvil supported working-surface.
 3. The apparatus of claim 1 wherein the track means comprises at least one substantially horizontal longitudinally extending rail maintained at substantially constant elevation loftily above the base member upper surface, there being a slider member slidably surrounding and longitudinally reciprocatably movable along said track rail, and the shoe member being ultimately connected to the slider member and co-reciprocatable therewith.
 4. The apparatus of claim 3 wherein the powering meAns comprises an electric motor including a revolvable eccentric-means thereon, and an elongate crank arm pivotably connected to said revolvable eccentric-means and also to said longitudinally reciprocatably movable slider member.
 5. The apparatus of claim 1 wherein the clamp-tensioning means comprises a substantially horizontal longitudinally extending elongate helical spring bearing against a clamp member and removably attached to the apparatus whereby the sheet material stretching tension is selectable depending upon the tension characteristics of the chosen helical spring.
 6. The apparatus of claim 5 wherein said elongate helical spring surrounds a substantially horizontal longitudinally extending spacer-rod having at least one terminus thereof removably attached to a clamp member to facilitate helical spring substitution for selectable tension upon the sheet material.
 7. The apparatus of claim 1 wherein the shoe member is attached to the lower portion of an upright support-bar, the support-bar upper portion being slidably surrounded by a tubular collar maintained at constant elevation above the base member upper surface, a set-screw passing through the tubular collar to vertically adjust the shoe member elevation whenever the apparatus operator is clamping andeclamping the tested sheet material, the shoe-tensioning means comprising a coil spring surrounding the support-bar between the shoe member and the upright tubular collar, said coil spring being removable from surrounding relationship with the support-bar whereby the shoe member downward force against the tested fabric is selectable depending upon the tension resiliency characteristics of the chosen coil spring.
 8. The apparatus of claim 7 wherein the shoe member comprises a removably connected bottom-panel portion of selectable texture and for making firm though reciprocatable contact with the tested sheet material.
 9. The apparatus of claim 1 adapted for simultaneously testing the same kind of textile fabric sheet material in the warp and weft directions thereof, there being a pair of anvil members in substantial parallelism and spaced on opposite sides of an imaginary longitudinally extending vertical-plane; wherein each of said anvil members is provided with a pair of terminal clamps and further comprises independent clamp-tensioning means for each pair; wherein the track means comprises a pair of substantially horizontal longitudinally extending elongate parallel rails located between the anvils and maintained at substantial co-elevation above the base member upper surface, each of said track rails being provided with a slider member slidably surrounding and longitudinally reciprocatably movable therealong, said slider members being attached together in co-reciprocatable relationship with a transversely extending web; wherein there is a pair of shoe members overlying the respective anvil members, each of said shoe members being ultimately connected to a sturdy columnar member extending rigidly uprightly from said transversely extending web; and wherein the powering means comprises an electric motor connected to the base member and including revolving eccentric means, and an elongate crank-arm lying along said imaginary upright-plane and being pivotably connected both to the motor shaft through the eccentric means carried thereby and also to the slider members connecting transverse web. 